A federal judge has ruled that Alabama—and the nation’s—third execution using nitrogen gas can go forward later this month.

The judge also rejected the inmate’s request to be given sedatives, or a fatal dose of fentanyl, before his execution, but left open the possibility of a mild sedative being prescribed for therapeutic reasons.

Carey Dale Grayson, 49, is set to die Nov. 21, within a 30-hour timeframe. Grayson was convicted with three other men for the brutal Feb. 22, 1994, slaying and mutilation of Vicki Lynn DeBlieux.

Alabama Death Row inmates Kenneth Smith and Alan Eugene Miller were executed in January and September, respectively, using nitrogen gas pumped through an industrial-type gas mask. Smith’s execution prompted calls from around the world to halt use of the method after he writhed on the gurney for several minutes.

But the Alabama Attorney General’s Office and the prison system has argued Smith was holding his breath, delaying the nitrogen from entering his body while he ran out of oxygen.

Miller’s execution was faster, and according to court records, he lost consciousness in minutes. Miller had reached a confidential settlement with the state prior to his execution, ending his legal fight to live.

Grayson, represented by lawyers from the Federal Public Defenders of the Middle District of Alabama, filed a lawsuit this summer challenging the state’s protocol on how it carries out a nitrogen gas execution.

There was a two-day hearing in the case in October, which Grayson attended in shackles.

On Wednesday, about a month after that hearing, the judge denied Grayson‘s request to call off the execution.

U.S. District Judge Austin Huffaker wrote that the prison system’s method of nitrogen executions “has been successfully used twice.”

Huffaker went on, “For clarity, the constitutionality of capital punishment is not before the Court. The death penalty is constitutional, and it is in force in Alabama. The unenviable task falls to this Court once again (for the third time) to decide whether execution by nitrogen hypoxia under the current protocol violates the Eighth Amendment; this time for Grayson’s stated reasons.”

The federal judge’s 53-page order detailed the executions of Smith and Miller, and Grayson’s argument.

Huffaker summarized the two previous nitrogen executions: “The evidence at the hearing showed that Kenneth Smith and Alan Miller became unconscious within minutes after the nitrogen gas started flowing, experienced agonal breathing after their loss of consciousness, and that Smith held his breath and struggled against the restraints while Miller did not.”

“… what that evidence did show (in Smith’s execution) was that the nitrogen hypoxia protocol was successful and resulted in death in less than 10 minutes and loss of consciousness in even less time,” he continued.

He described Miller’s execution as quick and said unconsciousness was reached in less than 2 minutes, “was void of struggles against the restraints, and with minimal body movement as compared to the Smith execution. Indeed, for as much as Smith’s execution was painted in the violent manner that it was, Miller’s execution was not.”

The Alabama Department of Corrections has only released the protocol in a heavily-redacted format, but Huffaker noted in his Wednesday order that the protocol does not call for a sedative prior to the gas being turned on.

Grayson’s lawyers had suggested two alternatives to the state’s plan: an updated nitrogen protocol that involves sedating the inmate, or an intramuscular injection of ketamine followed by a fatal dose of fentanyl.

But on Wednesday, the judge said the argument was “a classic battle of the experts, and a battle where one expert (Grayson’s expert) has no supporting case studies or other supporting medical testimony while the other (the state’s expert) does.

Huffaker also dismissed Alabama Attorney General Steve Marshall from the lawsuit, along with Gov. Kay Ivey.

Towards the end of his order, Huffaker recalled something that the Deputy Commissioner of Health Services, Deborah Crook, testified to last month. She said that the prison medical provider, YesCare, cannot participate in executions or provide drugs to be used in them.

But, the provider can fill other requests.

“Other courts have held that psychological pain or mental suffering cannot by itself support an Eighth Amendment claim… And of note on that issue, evidence was provided that Grayson could make a medical request for a sedative separate and apart from the execution protocol, and there is a strong possibility that such a request would be granted so long as the request is made for therapeutic purposes.”